/*
** $Id: lauxlib.c,v 1.289 2016/12/20 18:37:00 roberto Exp $
** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.h
*/

#define lauxlib_c
#define LUA_LIB

#include "lprefix.h"


#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


/*
** This file uses only the official API of Lua.
** Any function declared here could be written as an application function.
*/

#include "lua.h"

#include "lauxlib.h"


/*
** {======================================================
** Traceback
** =======================================================
*/


#define LEVELS1 10  /* size of the first part of the stack */
#define LEVELS2 11  /* size of the second part of the stack */



/*
** search for 'objidx' in table at index -1.
** return 1 + string at top if find a good name.
*/
static int findfield(lua_State *L, int objidx, int level)
{
    if (level == 0 || !lua_istable(L, -1))
        return 0;  /* not found */
    lua_pushnil(L);  /* start 'next' loop */
    while (lua_next(L, -2))    /* for each pair in table */
    {
        if (lua_type(L, -2) == LUA_TSTRING)    /* ignore non-string keys */
        {
            if (lua_rawequal(L, objidx, -1))    /* found object? */
            {
                lua_pop(L, 1);  /* remove value (but keep name) */
                return 1;
            }
            else if (findfield(L, objidx, level - 1))    /* try recursively */
            {
                lua_remove(L, -2);  /* remove table (but keep name) */
                lua_pushliteral(L, ".");
                lua_insert(L, -2);  /* place '.' between the two names */
                lua_concat(L, 3);
                return 1;
            }
        }
        lua_pop(L, 1);  /* remove value */
    }
    return 0;  /* not found */
}


/*
** Search for a name for a function in all loaded modules
*/
static int pushglobalfuncname(lua_State *L, lua_Debug *ar)
{
    int top = lua_gettop(L);
    lua_getinfo(L, "f", ar);  /* push function */
    lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
    if (findfield(L, top + 1, 2))
    {
        const char *name = lua_tostring(L, -1);
        if (strncmp(name, "_G.", 3) == 0)    /* name start with '_G.'? */
        {
            lua_pushstring(L, name + 3);  /* push name without prefix */
            lua_remove(L, -2);  /* remove original name */
        }
        lua_copy(L, -1, top + 1);  /* move name to proper place */
        lua_pop(L, 2);  /* remove pushed values */
        return 1;
    }
    else
    {
        lua_settop(L, top);  /* remove function and global table */
        return 0;
    }
}


static void pushfuncname(lua_State *L, lua_Debug *ar)
{
    if (pushglobalfuncname(L, ar))    /* try first a global name */
    {
        lua_pushfstring(L, "function '%s'", lua_tostring(L, -1));
        lua_remove(L, -2);  /* remove name */
    }
    else if (*ar->namewhat != '\0')  /* is there a name from code? */
        lua_pushfstring(L, "%s '%s'", ar->namewhat, ar->name);  /* use it */
    else if (*ar->what == 'm')  /* main? */
        lua_pushliteral(L, "main chunk");
    else if (*ar->what != 'C')  /* for Lua functions, use <file:line> */
        lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
    else  /* nothing left... */
        lua_pushliteral(L, "?");
}


static int lastlevel(lua_State *L)
{
    lua_Debug ar;
    int li = 1, le = 1;
    /* find an upper bound */
    while (lua_getstack(L, le, &ar))
    {
        li = le;
        le *= 2;
    }
    /* do a binary search */
    while (li < le)
    {
        int m = (li + le) / 2;
        if (lua_getstack(L, m, &ar)) li = m + 1;
        else le = m;
    }
    return le - 1;
}


LUALIB_API void luaL_traceback(lua_State *L, lua_State *L1,
                               const char *msg, int level)
{
    lua_Debug ar;
    int top = lua_gettop(L);
    int last = lastlevel(L1);
    int n1 = (last - level > LEVELS1 + LEVELS2) ? LEVELS1 : -1;
    if (msg)
        lua_pushfstring(L, "%s\n", msg);
    luaL_checkstack(L, 10, NULL);
    lua_pushliteral(L, "stack traceback:");
    while (lua_getstack(L1, level++, &ar))
    {
        if (n1-- == 0)    /* too many levels? */
        {
            lua_pushliteral(L, "\n\t...");  /* add a '...' */
            level = last - LEVELS2 + 1;  /* and skip to last ones */
        }
        else
        {
            lua_getinfo(L1, "Slnt", &ar);
            lua_pushfstring(L, "\n\t%s:", ar.short_src);
            if (ar.currentline > 0)
                lua_pushfstring(L, "%d:", ar.currentline);
            lua_pushliteral(L, " in ");
            pushfuncname(L, &ar);
            if (ar.istailcall)
                lua_pushliteral(L, "\n\t(...tail calls...)");
            lua_concat(L, lua_gettop(L) - top);
        }
    }
    lua_concat(L, lua_gettop(L) - top);
}

/* }====================================================== */


/*
** {======================================================
** Error-report functions
** =======================================================
*/

LUALIB_API int luaL_argerror(lua_State *L, int arg, const char *extramsg)
{
    lua_Debug ar;
    if (!lua_getstack(L, 0, &ar))  /* no stack frame? */
        return luaL_error(L, "bad argument #%d (%s)", arg, extramsg);
    lua_getinfo(L, "n", &ar);
    if (strcmp(ar.namewhat, "method") == 0)
    {
        arg--;  /* do not count 'self' */
        if (arg == 0)  /* error is in the self argument itself? */
            return luaL_error(L, "calling '%s' on bad self (%s)",
                              ar.name, extramsg);
    }
    if (ar.name == NULL)
        ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";
    return luaL_error(L, "bad argument #%d to '%s' (%s)",
                      arg, ar.name, extramsg);
}


static int typeerror(lua_State *L, int arg, const char *tname)
{
    const char *msg;
    const char *typearg;  /* name for the type of the actual argument */
    if (luaL_getmetafield(L, arg, "__name") == LUA_TSTRING)
        typearg = lua_tostring(L, -1);  /* use the given type name */
    else if (lua_type(L, arg) == LUA_TLIGHTUSERDATA)
        typearg = "light userdata";  /* special name for messages */
    else
        typearg = luaL_typename(L, arg);  /* standard name */
    msg = lua_pushfstring(L, "%s expected, got %s", tname, typearg);
    return luaL_argerror(L, arg, msg);
}


static void tag_error(lua_State *L, int arg, int tag)
{
    typeerror(L, arg, lua_typename(L, tag));
}


/*
** The use of 'lua_pushfstring' ensures this function does not
** need reserved stack space when called.
*/
LUALIB_API void luaL_where(lua_State *L, int level)
{
    lua_Debug ar;
    if (lua_getstack(L, level, &ar))    /* check function at level */
    {
        lua_getinfo(L, "Sl", &ar);  /* get info about it */
        if (ar.currentline > 0)    /* is there info? */
        {
            lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);
            return;
        }
    }
    lua_pushfstring(L, "");  /* else, no information available... */
}


/*
** Again, the use of 'lua_pushvfstring' ensures this function does
** not need reserved stack space when called. (At worst, it generates
** an error with "stack overflow" instead of the given message.)
*/
LUALIB_API int luaL_error(lua_State *L, const char *fmt, ...)
{
    va_list argp;
    va_start(argp, fmt);
    luaL_where(L, 1);
    lua_pushvfstring(L, fmt, argp);
    va_end(argp);
    lua_concat(L, 2);
    return lua_error(L);
}


LUALIB_API int luaL_fileresult(lua_State *L, int stat, const char *fname)
{
    int en = errno;  /* calls to Lua API may change this value */
    if (stat)
    {
        lua_pushboolean(L, 1);
        return 1;
    }
    else
    {
        lua_pushnil(L);
        if (fname)
            lua_pushfstring(L, "%s: %s", fname, strerror(en));
        else
            lua_pushstring(L, strerror(en));
        lua_pushinteger(L, en);
        return 3;
    }
}


#if !defined(l_inspectstat) /* { */

#if defined(LUA_USE_POSIX)

#include <sys/wait.h>

/*
** use appropriate macros to interpret 'pclose' return status
*/
#define l_inspectstat(stat,what)  \
   if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
   else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }

#else

#define l_inspectstat(stat,what)  /* no op */

#endif

#endif              /* } */


LUALIB_API int luaL_execresult(lua_State *L, int stat)
{
    const char *what = "exit";  /* type of termination */
    if (stat == -1)  /* error? */
        return luaL_fileresult(L, 0, NULL);
    else
    {
        l_inspectstat(stat, what);  /* interpret result */
        if (*what == 'e' && stat == 0)  /* successful termination? */
            lua_pushboolean(L, 1);
        else
            lua_pushnil(L);
        lua_pushstring(L, what);
        lua_pushinteger(L, stat);
        return 3;  /* return true/nil,what,code */
    }
}

/* }====================================================== */


/*
** {======================================================
** Userdata's metatable manipulation
** =======================================================
*/

LUALIB_API int luaL_newmetatable(lua_State *L, const char *tname)
{
    if (luaL_getmetatable(L, tname) != LUA_TNIL)  /* name already in use? */
        return 0;  /* leave previous value on top, but return 0 */
    lua_pop(L, 1);
    lua_createtable(L, 0, 2);  /* create metatable */
    lua_pushstring(L, tname);
    lua_setfield(L, -2, "__name");  /* metatable.__name = tname */
    lua_pushvalue(L, -1);
    lua_setfield(L, LUA_REGISTRYINDEX, tname);  /* registry.name = metatable */
    return 1;
}


LUALIB_API void luaL_setmetatable(lua_State *L, const char *tname)
{
    luaL_getmetatable(L, tname);
    lua_setmetatable(L, -2);
}


LUALIB_API void *luaL_testudata(lua_State *L, int ud, const char *tname)
{
    void *p = lua_touserdata(L, ud);
    if (p != NULL)    /* value is a userdata? */
    {
        if (lua_getmetatable(L, ud))    /* does it have a metatable? */
        {
            luaL_getmetatable(L, tname);  /* get correct metatable */
            if (!lua_rawequal(L, -1, -2))  /* not the same? */
                p = NULL;  /* value is a userdata with wrong metatable */
            lua_pop(L, 2);  /* remove both metatables */
            return p;
        }
    }
    return NULL;  /* value is not a userdata with a metatable */
}


LUALIB_API void *luaL_checkudata(lua_State *L, int ud, const char *tname)
{
    void *p = luaL_testudata(L, ud, tname);
    if (p == NULL) typeerror(L, ud, tname);
    return p;
}

/* }====================================================== */


/*
** {======================================================
** Argument check functions
** =======================================================
*/

LUALIB_API int luaL_checkoption(lua_State *L, int arg, const char *def,
                                const char *const lst[])
{
    const char *name = (def) ? luaL_optstring(L, arg, def) :
                       luaL_checkstring(L, arg);
    int i;
    for (i = 0; lst[i]; i++)
        if (strcmp(lst[i], name) == 0)
            return i;
    return luaL_argerror(L, arg,
                         lua_pushfstring(L, "invalid option '%s'", name));
}


/*
** Ensures the stack has at least 'space' extra slots, raising an error
** if it cannot fulfill the request. (The error handling needs a few
** extra slots to format the error message. In case of an error without
** this extra space, Lua will generate the same 'stack overflow' error,
** but without 'msg'.)
*/
LUALIB_API void luaL_checkstack(lua_State *L, int space, const char *msg)
{
    if (!lua_checkstack(L, space))
    {
        if (msg)
            luaL_error(L, "stack overflow (%s)", msg);
        else
            luaL_error(L, "stack overflow");
    }
}


LUALIB_API void luaL_checktype(lua_State *L, int arg, int t)
{
    if (lua_type(L, arg) != t)
        tag_error(L, arg, t);
}


LUALIB_API void luaL_checkany(lua_State *L, int arg)
{
    if (lua_type(L, arg) == LUA_TNONE)
        luaL_argerror(L, arg, "value expected");
}


LUALIB_API const char *luaL_checklstring(lua_State *L, int arg, size_t *len)
{
    const char *s = lua_tolstring(L, arg, len);
    if (!s) tag_error(L, arg, LUA_TSTRING);
    return s;
}


LUALIB_API const char *luaL_optlstring(lua_State *L, int arg,
                                       const char *def, size_t *len)
{
    if (lua_isnoneornil(L, arg))
    {
        if (len)
            *len = (def ? strlen(def) : 0);
        return def;
    }
    else return luaL_checklstring(L, arg, len);
}


LUALIB_API lua_Number luaL_checknumber(lua_State *L, int arg)
{
    int isnum;
    lua_Number d = lua_tonumberx(L, arg, &isnum);
    if (!isnum)
        tag_error(L, arg, LUA_TNUMBER);
    return d;
}


LUALIB_API lua_Number luaL_optnumber(lua_State *L, int arg, lua_Number def)
{
    return luaL_opt(L, luaL_checknumber, arg, def);
}


static void interror(lua_State *L, int arg)
{
    if (lua_isnumber(L, arg))
        luaL_argerror(L, arg, "number has no integer representation");
    else
        tag_error(L, arg, LUA_TNUMBER);
}


LUALIB_API lua_Integer luaL_checkinteger(lua_State *L, int arg)
{
    int isnum;
    lua_Integer d = lua_tointegerx(L, arg, &isnum);
    if (!isnum)
    {
        interror(L, arg);
    }
    return d;
}


LUALIB_API lua_Integer luaL_optinteger(lua_State *L, int arg,
                                       lua_Integer def)
{
    return luaL_opt(L, luaL_checkinteger, arg, def);
}

/* }====================================================== */


/*
** {======================================================
** Generic Buffer manipulation
** =======================================================
*/

/* userdata to box arbitrary data */
typedef struct UBox
{
    void *box;
    size_t bsize;
} UBox;


static void *resizebox(lua_State *L, int idx, size_t newsize)
{
    void *ud;
    lua_Alloc allocf = lua_getallocf(L, &ud);
    UBox *box = (UBox *)lua_touserdata(L, idx);
    void *temp = allocf(ud, box->box, box->bsize, newsize);
    if (temp == NULL && newsize > 0)    /* allocation error? */
    {
        resizebox(L, idx, 0);  /* free buffer */
        luaL_error(L, "not enough memory for buffer allocation");
    }
    box->box = temp;
    box->bsize = newsize;
    return temp;
}


static int boxgc(lua_State *L)
{
    resizebox(L, 1, 0);
    return 0;
}


static void *newbox(lua_State *L, size_t newsize)
{
    UBox *box = (UBox *)lua_newuserdata(L, sizeof(UBox));
    box->box = NULL;
    box->bsize = 0;
    if (luaL_newmetatable(L, "LUABOX"))    /* creating metatable? */
    {
        lua_pushcfunction(L, boxgc);
        lua_setfield(L, -2, "__gc");  /* metatable.__gc = boxgc */
    }
    lua_setmetatable(L, -2);
    return resizebox(L, -1, newsize);
}


/*
** check whether buffer is using a userdata on the stack as a temporary
** buffer
*/
#define buffonstack(B)  ((B)->b != (B)->initb)


/*
** returns a pointer to a free area with at least 'sz' bytes
*/
LUALIB_API char *luaL_prepbuffsize(luaL_Buffer *B, size_t sz)
{
    lua_State *L = B->L;
    if (B->size - B->n < sz)    /* not enough space? */
    {
        char *newbuff;
        size_t newsize = B->size * 2;  /* double buffer size */
        if (newsize - B->n < sz)  /* not big enough? */
            newsize = B->n + sz;
        if (newsize < B->n || newsize - B->n < sz)
            luaL_error(L, "buffer too large");
        /* create larger buffer */
        if (buffonstack(B))
            newbuff = (char *)resizebox(L, -1, newsize);
        else    /* no buffer yet */
        {
            newbuff = (char *)newbox(L, newsize);
            memcpy(newbuff, B->b, B->n * sizeof(char));  /* copy original content */
        }
        B->b = newbuff;
        B->size = newsize;
    }
    return &B->b[B->n];
}


LUALIB_API void luaL_addlstring(luaL_Buffer *B, const char *s, size_t l)
{
    if (l > 0)    /* avoid 'memcpy' when 's' can be NULL */
    {
        char *b = luaL_prepbuffsize(B, l);
        memcpy(b, s, l * sizeof(char));
        luaL_addsize(B, l);
    }
}


LUALIB_API void luaL_addstring(luaL_Buffer *B, const char *s)
{
    luaL_addlstring(B, s, strlen(s));
}


LUALIB_API void luaL_pushresult(luaL_Buffer *B)
{
    lua_State *L = B->L;
    lua_pushlstring(L, B->b, B->n);
    if (buffonstack(B))
    {
        resizebox(L, -2, 0);  /* delete old buffer */
        lua_remove(L, -2);  /* remove its header from the stack */
    }
}


LUALIB_API void luaL_pushresultsize(luaL_Buffer *B, size_t sz)
{
    luaL_addsize(B, sz);
    luaL_pushresult(B);
}


LUALIB_API void luaL_addvalue(luaL_Buffer *B)
{
    lua_State *L = B->L;
    size_t l;
    const char *s = lua_tolstring(L, -1, &l);
    if (buffonstack(B))
        lua_insert(L, -2);  /* put value below buffer */
    luaL_addlstring(B, s, l);
    lua_remove(L, (buffonstack(B)) ? -2 : -1);  /* remove value */
}


LUALIB_API void luaL_buffinit(lua_State *L, luaL_Buffer *B)
{
    B->L = L;
    B->b = B->initb;
    B->n = 0;
    B->size = LUAL_BUFFERSIZE;
}


LUALIB_API char *luaL_buffinitsize(lua_State *L, luaL_Buffer *B, size_t sz)
{
    luaL_buffinit(L, B);
    return luaL_prepbuffsize(B, sz);
}

/* }====================================================== */


/*
** {======================================================
** Reference system
** =======================================================
*/

/* index of free-list header */
#define freelist    0


LUALIB_API int luaL_ref(lua_State *L, int t)
{
    int ref;
    if (lua_isnil(L, -1))
    {
        lua_pop(L, 1);  /* remove from stack */
        return LUA_REFNIL;  /* 'nil' has a unique fixed reference */
    }
    t = lua_absindex(L, t);
    lua_rawgeti(L, t, freelist);  /* get first free element */
    ref = (int)lua_tointeger(L, -1);  /* ref = t[freelist] */
    lua_pop(L, 1);  /* remove it from stack */
    if (ref != 0)    /* any free element? */
    {
        lua_rawgeti(L, t, ref);  /* remove it from list */
        lua_rawseti(L, t, freelist);  /* (t[freelist] = t[ref]) */
    }
    else  /* no free elements */
        ref = (int)lua_rawlen(L, t) + 1;  /* get a new reference */
    lua_rawseti(L, t, ref);
    return ref;
}


LUALIB_API void luaL_unref(lua_State *L, int t, int ref)
{
    if (ref >= 0)
    {
        t = lua_absindex(L, t);
        lua_rawgeti(L, t, freelist);
        lua_rawseti(L, t, ref);  /* t[ref] = t[freelist] */
        lua_pushinteger(L, ref);
        lua_rawseti(L, t, freelist);  /* t[freelist] = ref */
    }
}

/* }====================================================== */


/*
** {======================================================
** Load functions
** =======================================================
*/

typedef struct LoadF
{
    int n;  /* number of pre-read characters */
    FILE *f;  /* file being read */
    char buff[BUFSIZ];  /* area for reading file */
} LoadF;


static const char *getF(lua_State *L, void *ud, size_t *size)
{
    LoadF *lf = (LoadF *)ud;
    (void)L;  /* not used */
    if (lf->n > 0)    /* are there pre-read characters to be read? */
    {
        *size = lf->n;  /* return them (chars already in buffer) */
        lf->n = 0;  /* no more pre-read characters */
    }
    else    /* read a block from file */
    {
        /* 'fread' can return > 0 *and* set the EOF flag. If next call to
           'getF' called 'fread', it might still wait for user input.
           The next check avoids this problem. */
        if (feof(lf->f)) return NULL;
        *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */
    }
    return lf->buff;
}


static int errfile(lua_State *L, const char *what, int fnameindex)
{
    const char *serr = strerror(errno);
    const char *filename = lua_tostring(L, fnameindex) + 1;
    lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
    lua_remove(L, fnameindex);
    return LUA_ERRFILE;
}


static int skipBOM(LoadF *lf)
{
    const char *p = "\xEF\xBB\xBF";  /* UTF-8 BOM mark */
    int c;
    lf->n = 0;
    do
    {
        c = getc(lf->f);
        if (c == EOF || c != *(const unsigned char *)p++) return c;
        lf->buff[lf->n++] = c;  /* to be read by the parser */
    }
    while (*p != '\0');
    lf->n = 0;  /* prefix matched; discard it */
    return getc(lf->f);  /* return next character */
}


/*
** reads the first character of file 'f' and skips an optional BOM mark
** in its beginning plus its first line if it starts with '#'. Returns
** true if it skipped the first line.  In any case, '*cp' has the
** first "valid" character of the file (after the optional BOM and
** a first-line comment).
*/
static int skipcomment(LoadF *lf, int *cp)
{
    int c = *cp = skipBOM(lf);
    if (c == '#')    /* first line is a comment (Unix exec. file)? */
    {
        do    /* skip first line */
        {
            c = getc(lf->f);
        }
        while (c != EOF && c != '\n');
        *cp = getc(lf->f);  /* skip end-of-line, if present */
        return 1;  /* there was a comment */
    }
    else return 0;  /* no comment */
}


LUALIB_API int luaL_loadfilex(lua_State *L, const char *filename,
                              const char *mode)
{
    LoadF lf;
    int status, readstatus;
    int c;
    int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
    if (filename == NULL)
    {
        lua_pushliteral(L, "=stdin");
        lf.f = stdin;
    }
    else
    {
        lua_pushfstring(L, "@%s", filename);
        lf.f = fopen(filename, "r");
        if (lf.f == NULL) return errfile(L, "open", fnameindex);
    }
    if (skipcomment(&lf, &c))  /* read initial portion */
        lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */
    if (c == LUA_SIGNATURE[0] && filename)    /* binary file? */
    {
        lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
        if (lf.f == NULL) return errfile(L, "reopen", fnameindex);
        skipcomment(&lf, &c);  /* re-read initial portion */
    }
    if (c != EOF)
        lf.buff[lf.n++] = c;  /* 'c' is the first character of the stream */
    status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);
    readstatus = ferror(lf.f);
    if (filename) fclose(lf.f);  /* close file (even in case of errors) */
    if (readstatus)
    {
        lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
        return errfile(L, "read", fnameindex);
    }
    lua_remove(L, fnameindex);
    return status;
}


typedef struct LoadS
{
    const char *s;
    size_t size;
} LoadS;


static const char *getS(lua_State *L, void *ud, size_t *size)
{
    LoadS *ls = (LoadS *)ud;
    (void)L;  /* not used */
    if (ls->size == 0) return NULL;
    *size = ls->size;
    ls->size = 0;
    return ls->s;
}


LUALIB_API int luaL_loadbufferx(lua_State *L, const char *buff, size_t size,
                                const char *name, const char *mode)
{
    LoadS ls;
    ls.s = buff;
    ls.size = size;
    return lua_load(L, getS, &ls, name, mode);
}


LUALIB_API int luaL_loadstring(lua_State *L, const char *s)
{
    return luaL_loadbuffer(L, s, strlen(s), s);
}

/* }====================================================== */



LUALIB_API int luaL_getmetafield(lua_State *L, int obj, const char *event)
{
    if (!lua_getmetatable(L, obj))  /* no metatable? */
        return LUA_TNIL;
    else
    {
        int tt;
        lua_pushstring(L, event);
        tt = lua_rawget(L, -2);
        if (tt == LUA_TNIL)  /* is metafield nil? */
            lua_pop(L, 2);  /* remove metatable and metafield */
        else
            lua_remove(L, -2);  /* remove only metatable */
        return tt;  /* return metafield type */
    }
}


LUALIB_API int luaL_callmeta(lua_State *L, int obj, const char *event)
{
    obj = lua_absindex(L, obj);
    if (luaL_getmetafield(L, obj, event) == LUA_TNIL)  /* no metafield? */
        return 0;
    lua_pushvalue(L, obj);
    lua_call(L, 1, 1);
    return 1;
}


LUALIB_API lua_Integer luaL_len(lua_State *L, int idx)
{
    lua_Integer l;
    int isnum;
    lua_len(L, idx);
    l = lua_tointegerx(L, -1, &isnum);
    if (!isnum)
        luaL_error(L, "object length is not an integer");
    lua_pop(L, 1);  /* remove object */
    return l;
}


LUALIB_API const char *luaL_tolstring(lua_State *L, int idx, size_t *len)
{
    if (luaL_callmeta(L, idx, "__tostring"))    /* metafield? */
    {
        if (!lua_isstring(L, -1))
            luaL_error(L, "'__tostring' must return a string");
    }
    else
    {
        switch (lua_type(L, idx))
        {
        case LUA_TNUMBER:
        {
            if (lua_isinteger(L, idx))
                lua_pushfstring(L, "%I", (LUAI_UACINT)lua_tointeger(L, idx));
            else
                lua_pushfstring(L, "%f", (LUAI_UACNUMBER)lua_tonumber(L, idx));
            break;
        }
        case LUA_TSTRING:
            lua_pushvalue(L, idx);
            break;
        case LUA_TBOOLEAN:
            lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));
            break;
        case LUA_TNIL:
            lua_pushliteral(L, "nil");
            break;
        default:
        {
            int tt = luaL_getmetafield(L, idx, "__name");  /* try name */
            const char *kind = (tt == LUA_TSTRING) ? lua_tostring(L, -1) :
                               luaL_typename(L, idx);
            lua_pushfstring(L, "%s: %p", kind, lua_topointer(L, idx));
            if (tt != LUA_TNIL)
                lua_remove(L, -2);  /* remove '__name' */
            break;
        }
        }
    }
    return lua_tolstring(L, -1, len);
}


/*
** {======================================================
** Compatibility with 5.1 module functions
** =======================================================
*/
#if defined(LUA_COMPAT_MODULE)

static const char *luaL_findtable(lua_State *L, int idx,
                                  const char *fname, int szhint)
{
    const char *e;
    if (idx) lua_pushvalue(L, idx);
    do
    {
        e = strchr(fname, '.');
        if (e == NULL) e = fname + strlen(fname);
        lua_pushlstring(L, fname, e - fname);
        if (lua_rawget(L, -2) == LUA_TNIL)    /* no such field? */
        {
            lua_pop(L, 1);  /* remove this nil */
            lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */
            lua_pushlstring(L, fname, e - fname);
            lua_pushvalue(L, -2);
            lua_settable(L, -4);  /* set new table into field */
        }
        else if (!lua_istable(L, -1))    /* field has a non-table value? */
        {
            lua_pop(L, 2);  /* remove table and value */
            return fname;  /* return problematic part of the name */
        }
        lua_remove(L, -2);  /* remove previous table */
        fname = e + 1;
    }
    while (*e == '.');
    return NULL;
}


/*
** Count number of elements in a luaL_Reg list.
*/
static int libsize(const luaL_Reg *l)
{
    int size = 0;
    for (; l && l->name; l++) size++;
    return size;
}


/*
** Find or create a module table with a given name. The function
** first looks at the LOADED table and, if that fails, try a
** global variable with that name. In any case, leaves on the stack
** the module table.
*/
LUALIB_API void luaL_pushmodule(lua_State *L, const char *modname,
                                int sizehint)
{
    luaL_findtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE, 1);
    if (lua_getfield(L, -1, modname) != LUA_TTABLE)    /* no LOADED[modname]? */
    {
        lua_pop(L, 1);  /* remove previous result */
        /* try global variable (and create one if it does not exist) */
        lua_pushglobaltable(L);
        if (luaL_findtable(L, 0, modname, sizehint) != NULL)
            luaL_error(L, "name conflict for module '%s'", modname);
        lua_pushvalue(L, -1);
        lua_setfield(L, -3, modname);  /* LOADED[modname] = new table */
    }
    lua_remove(L, -2);  /* remove LOADED table */
}


LUALIB_API void luaL_openlib(lua_State *L, const char *libname,
                             const luaL_Reg *l, int nup)
{
    luaL_checkversion(L);
    if (libname)
    {
        luaL_pushmodule(L, libname, libsize(l));  /* get/create library table */
        lua_insert(L, -(nup + 1));  /* move library table to below upvalues */
    }
    if (l)
        luaL_setfuncs(L, l, nup);
    else
        lua_pop(L, nup);  /* remove upvalues */
}

#endif
/* }====================================================== */

/*
** set functions from list 'l' into table at top - 'nup'; each
** function gets the 'nup' elements at the top as upvalues.
** Returns with only the table at the stack.
*/
LUALIB_API void luaL_setfuncs(lua_State *L, const luaL_Reg *l, int nup)
{
    luaL_checkstack(L, nup, "too many upvalues");
    for (; l->name != NULL; l++)    /* fill the table with given functions */
    {
        int i;
        for (i = 0; i < nup; i++)  /* copy upvalues to the top */
            lua_pushvalue(L, -nup);
        lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
        lua_setfield(L, -(nup + 2), l->name);
    }
    lua_pop(L, nup);  /* remove upvalues */
}


/*
** ensure that stack[idx][fname] has a table and push that table
** into the stack
*/
LUALIB_API int luaL_getsubtable(lua_State *L, int idx, const char *fname)
{
    if (lua_getfield(L, idx, fname) == LUA_TTABLE)
        return 1;  /* table already there */
    else
    {
        lua_pop(L, 1);  /* remove previous result */
        idx = lua_absindex(L, idx);
        lua_newtable(L);
        lua_pushvalue(L, -1);  /* copy to be left at top */
        lua_setfield(L, idx, fname);  /* assign new table to field */
        return 0;  /* false, because did not find table there */
    }
}


/*
** Stripped-down 'require': After checking "loaded" table, calls 'openf'
** to open a module, registers the result in 'package.loaded' table and,
** if 'glb' is true, also registers the result in the global table.
** Leaves resulting module on the top.
*/
LUALIB_API void luaL_requiref(lua_State *L, const char *modname,
                              lua_CFunction openf, int glb)
{
    luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
    lua_getfield(L, -1, modname);  /* LOADED[modname] */
    if (!lua_toboolean(L, -1))    /* package not already loaded? */
    {
        lua_pop(L, 1);  /* remove field */
        lua_pushcfunction(L, openf);
        lua_pushstring(L, modname);  /* argument to open function */
        lua_call(L, 1, 1);  /* call 'openf' to open module */
        lua_pushvalue(L, -1);  /* make copy of module (call result) */
        lua_setfield(L, -3, modname);  /* LOADED[modname] = module */
    }
    lua_remove(L, -2);  /* remove LOADED table */
    if (glb)
    {
        lua_pushvalue(L, -1);  /* copy of module */
        lua_setglobal(L, modname);  /* _G[modname] = module */
    }
}


LUALIB_API const char *luaL_gsub(lua_State *L, const char *s, const char *p,
                                 const char *r)
{
    const char *wild;
    size_t l = strlen(p);
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    while ((wild = strstr(s, p)) != NULL)
    {
        luaL_addlstring(&b, s, wild - s);  /* push prefix */
        luaL_addstring(&b, r);  /* push replacement in place of pattern */
        s = wild + l;  /* continue after 'p' */
    }
    luaL_addstring(&b, s);  /* push last suffix */
    luaL_pushresult(&b);
    return lua_tostring(L, -1);
}


static void *l_alloc(void *ud, void *ptr, size_t osize, size_t nsize)
{
    (void)ud;
    (void)osize;  /* not used */
    if (nsize == 0)
    {
        free(ptr);
        return NULL;
    }
    else
        return realloc(ptr, nsize);
}


static int panic(lua_State *L)
{
    lua_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n",
                         lua_tostring(L, -1));
    return 0;  /* return to Lua to abort */
}


LUALIB_API lua_State *luaL_newstate(void)
{
    lua_State *L = lua_newstate(l_alloc, NULL);
    if (L) lua_atpanic(L, &panic);
    return L;
}


LUALIB_API void luaL_checkversion_(lua_State *L, lua_Number ver, size_t sz)
{
    const lua_Number *v = lua_version(L);
    if (sz != LUAL_NUMSIZES)  /* check numeric types */
        luaL_error(L, "core and library have incompatible numeric types");
    if (v != lua_version(NULL))
        luaL_error(L, "multiple Lua VMs detected");
    else if (*v != ver)
        luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f",
                   (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)*v);
}

